Volume 9 Issue 7, July 2013

NMR analysis of the conformational energy landscape of the catabolite activator protein suggests that allosteric inhibition can be achieved by blocking access to elusive high-energy states of proteins.

Elusive pan-phosphohistidine (pHis) antibodies have been generated using a hydrolytically stable triazolyl-phosphonate hapten, promising to substantially accelerate efforts to better understand the role of pHis in biology.

Formamidopyrimidine residues are damaged purines that retain the same Watson-Crick hydrogen-bonding face found in the parent nucleobase, yet these lesions are mutagenic. Crystallographic evidence suggests molecular mechanisms by which these lesions 'mispair' to generate mutations during DNA replication.

Transduction of extracellular signals by cilia requires regulated entry of pathway components. A new study uses chemical dimerization to induce diffusion and identifies size-dependent soluble diffusion rates consistent with a sieve-like barrier with 8-nm pore radii at the ciliary base.

Studies of histidine phosphorylation have been limited owing to a lack of appropriate tools. The synthesis of a stable phosphohistidine mimic now leads to a pan antibody, enabling detection and further functional investigations of this little-known post-translational modification.

The radical SAM enzyme Cfr catalyzes methylation of a ribosomal adenosine, causing broad antibiotic resistance. EPR and ENDOR techniques now provide direct evidence for the proposed enzymatic mechanism by detecting a central crosslinked intermediate in which a radical is located on the nucleotide.

ATP-competitive RAF kinase inhibitors stabilize a closed and rigid active conformation of the RAF kinase domain, which leads to RAF dimerization and allosteric activation of the inhibitor-free protomer.

Chemically inducible diffusion trap at cilia (CIDTc), a method to trap proteins in the cilia, was applied to study the kinetics of protein accumulation and reveal a molecular sieve at the ciliary base. CIDTc can also be applied to study signaling pathways in the cilia.

Compounds that restore function to the cystic fibrosis–linked ΔF508 allele of CFTR can be classified on the basis of three corrector functions, representing different targets within the five domains of the channel protein. Combinations of individual compounds in the three classes can restore considerable function to the mutant channel.

Certain oxidative DNA lesions adopt altered conformational preferences that lead to mutations during replication. Biochemical and structural data reveal that for formamidopyrimidine lesions, tautomerization and altered base pair geometry in the DNA polymerase active site, rather than changes in glycosidic torsion angle, direct the mutagenicity of these lesions.

Advanced NMR studies of catabolite activator protein show that allosteric inhibitors can prevent conformational changes needed for a protein to bind its ligand, offering an explanation for why these inhibitors may not appear to cause any effect when monitored using static techniques.